The present invention generally relates to a system for the effective containment of fluids, primarily precipitation and effluent arising from operations at a given site, and for management of the contained fluids. The system is particularly well suited to sites intended for gas and oil well drilling, but is also useful with sites for performing other functions that can benefit from improved fluid containment and management, including water, sewage and storm water systems.
There are currently no consistent regulatory standards, from state to state, governing the construction of environmental protection systems used in the oil and gas exploration and extraction industries. About 80% of states require a raised dike system around storage tanks for produced water and separator tanks for receiving oil, gas and produced water. Some, but not all states require impermeable liners within the dikes. Fluid storage basins are also used for the temporary storage of well production fluids and produced water. However, these basins are lined with an impermeable membrane that is typically not resistant to puncture or shear stresses.
Typical protection for the well pad itself is often limited to a peripheral dike or berm surrounding the well pad. As an added measure of protection, some installations have used a flexible, 20 mil plastic sheet laid over a 2 foot thick layer of a modified base material, typically limestone. In practice, however, such installations have been found to be susceptible to tire damage from the many heavy vehicles often used at such sites, often having weights on the order of 80,000 lbs., particularly for pressurized fracturing (generally referred to as “fracking”) operations and for water transportation, as well as puncturing by metal drilling system components and other hazardous objects found on well sites.
Moreover, such membrane installations are temporary and are replaced each time there is a well workover, a re-fracking or a new drilling location on the pad, and allow water to accumulate and pool. Such membranes are also slippery to work on, and can freeze in the winter months, creating a work hazard. There is also little scientific monitoring of leakage from such fluid detention basins. Leaks are detected, if at all, by visually detecting drops in fluid levels.
As a consequence, current practices are somewhat haphazard, and have been less than adequate for their intended purpose, failing to provide an appropriate level of environmental protection from contaminants. This has recently been exhibited by single, vertically-drilled wells, as evidenced by some of the recent blow-outs and mishaps encountered in the Marcellus Shale drilling area.
Various technologies have recently been developed for use in the rapidly developing on-shore natural gas extraction industry. Such technologies have in many circumstances made current environmental protection practices wholly inadequate. For example, new drilling techniques allow a drill string to bore down to a gas-bearing shale bed and then change direction, to drill horizontally through the shale bed, often for as many as several thousand feet. Shale, however, is not highly permeable to the gas it contains, and high pressure fracking techniques must be used to open up the shale layers (sedimentary rock) and inject sand and similarly sized particles between the layers to hold them open and provide significantly increased gas flows. Directional drilling techniques can be used to allow a single, although significantly enlarged, well pad to house as many well heads as are needed to properly develop a particular site.
Such processes require the use of significant amounts of water. As a result, such installations, particularly those involving multiple wells on a single well pad, require increased fluid management resources. Horizontal well fracking takes place over thousands of feet of well bore, requiring ten, twenty, or more times the volume of fracking water that would be used in a conventional vertical well, because a vertical well intersects the shale bed for only a hundred feet or so. As much as five million gallons of water can be used in the fracking of a single well, and there can be as many as ten wells per well pad site.
Current spill management practices are wholly inadequate for protecting the environment from potential spills and leaks at these volumes, which in turn leads to the need for a new well pad environmental protection protocol.
In addition to the greatly increased volumes of fluid that can potentially spill, or leak at the well pad, the need for improved environmental protection further arises from recent high levels of exploration and development in areas where there has previously been little or no drilling. This raises considerable concerns over possible environmental damage, particularly to potable water supplies. Further complicating this is the increase in the type, number and volume of chemicals used in such well development techniques which, according to the industry, is said to include over 750 different chemicals.
Moreover, such gas wells typically have a shorter operating life than oil wells. Production levels can fall off quickly, even though shale bed gases have not been depleted significantly. This can require a significant level of re-fracking into the same well, which can in turn lead to hazards resulting from the increased number of re-fracking procedures needed. Also, as an example, and for natural gas development only in the Marcellus shales, forecasts of the number of wells to be drilled have ranged from 1,400 to 2,700 in the year 2011, from 1,600 to 3,900 for the year 2015, and from 1,700 to 4,800 for the year 2020.
A reliable process and associated system is essential for the protection of groundwater and the surrounding land from pollution. This can be achieved only through 100% containment of spills and leaks throughout all well drilling and development operations. Fracking operations, while using primarily fresh water to break open shale formations, also use several thousands of gallons of chemicals, ranging from acids to soaps to biocides and more. This would require the capacity to contain a 100,000 gallon spill within each sub-well pad section.